June13class

Minimum Rules for Frequency Tables

1. same size intervals
2. continuous intervals
3. highest scores on top
4. 10-12 intervals [others say 6 - 8]
5. Odd interval scale - so that the mean can be determined easier
6. lower score limit should be a mulitiple of the interval size, ex. interval set 3 then lower score set 21.

Steps for constructing Frequency tables

1. determine lowest & highest score
2. find range (highest score - lowest score)
3. divide range by 10 & 20 (or 6 & 8) to determine acceptable widths
4. determine lowest class interval
5. list all intervals from lowest to highest
6. count each score into its interval - these are absolute frequencies

For Excel
1. Highlight all the cells containing data - hit f2 key, then control shift enter

Percentile Rank
% of cases that fall below a given score OR the score below which % of cases fall